Nanometer-size-particle production apparatus, nanometer-size-particle production process, nanometer-size particles, zinc/zinc oxide nanometer-size particles, and magnesium hydroxide nanometer-size particles

ABSTRACT

A nanometer-size-particle production apparatus is provided which can prevent the occurrence of waste fluids, and which makes quick and continuous syntheses feasible while suppressing damages to the electrode. 
     The present invention is a nanometer-size-particle production apparatus for synthesizing nanometer-size particles in a liquid by means of plasma in liquid, and comprises: a container for accommodating the liquid therein; an electromagnetic-wave generation device for generating a high-frequency wave, or a microwave; an electrode conductor whose leading end makes contact with the liquid to supply the high-frequency wave or the microwave to the liquid; a covering portion being disposed into the liquid so as to cover a leading-end upside of the electrode conductor; a metallic chip being composed of a metal making a raw material of nanometer-size particles, and having a leading end that is disposed to face to a leading-end section of the electrode conductor; and a feed device for feeding out the leading end of the metallic chip with respect to the leading-end section of the electrode conductor; the leading end of the electrode conductor having a configuration that is a non-edge configuration; and the electrode conductor, except for the leading end, having an axially-orthogonal cross-sectional area that is larger than an axially-orthogonal cross-sectional area of the metallic chip.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/JP2012/002799, filed on Apr. 24, 2012, which claims priority fromJapanese Patent Application No. 2011-101531, filed on Apr. 28, 2011, thecontents of all of which are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

The present invention is one which relates to nanometer-size particles,and to a production apparatus and production process for nanometer-sizeparticles.

BACKGROUND ART

Since nanometer-size particles have physical properties that metallicchips do not have, the studies on nanometer-size particles have beenadvancing recently. Although a vapor-phase oxidation method has beenavailable for the synthesis of nanometer-size particles, it is difficultto collect the resulting nanometer-size particles by this method. Hence,techniques for synthesizing nanometer-size particles utilizing plasma inliquid are set forth in Japanese Unexamined Patent Publication (KOKAI)Gazette No. 2008-13810 (i.e., Patent Literature No. 1) and JapaneseUnexamined Patent Publication (KOKAI) Gazette No. 2010-121193 (i.e.,Patent Literature No. 2), for instance.

RELATED TECHNICAL LITERATURE Patent Literature

Patent Literature No. 1: Japanese Unexamined Patent Publication (KOKAI)Gazette No. 2008-13810; and

Patent Literature No. 2: Japanese Unexamined Patent Publication (KOKAI)Gazette No. 2010-121193

SUMMARY OF THE INVENTION Assignment to be Solved by the Invention

However, waste fluids have arisen in the method like thoseaforementioned in which nanometer-size particles are synthesized whilegenerating plasma in an ionic liquid including elements that make theraw materials of nanometer-size particles. Moreover, in the productionof nanometer-size particles, it has been required to synthesize themquickly and continuously while suppressing damages to the electrode.

The present invention is one which has been done in view of suchcircumstances. Accordingly, it is an object to provide ananometer-size-particle production apparatus and nanometer-size-particleproduction process which can prevent the occurrence of waste fluids, andwhich makes quick and continuous syntheses feasible while suppressingdamages to the electrode. Moreover, it is another object to providenanometer-size particles having a specific structure or configurationthat have been produced by means of the present apparatus or presentprocess.

Means for Solving the Assignment

The present invention is a nanometer-size-particle production apparatusfor synthesizing nanometer-size particles in a liquid by means of plasmain liquid, and comprises:

-   -   a container for accommodating said liquid therein;    -   an electromagnetic-wave generation device for generating a        high-frequency wave, or a microwave;    -   an electrode conductor whose leading end makes contact with said        liquid to supply said high-frequency wave or said microwave to        said liquid;    -   a covering portion being disposed into said liquid so as to        cover a leading-end upside of said electrode conductor;    -   a metallic chip being composed of a metal making a raw material        of nanometer-size particles, and having a leading end that is        disposed to face to the leading end of said electrode conductor;        and    -   a feed device for feeding out the leading end of said metallic        chip with respect to the leading end of said electrode        conductor;    -   a leading-end section of said electrode conductor having a        configuration that is a non-edge configuration; and    -   said electrode conductor, except for the leading-end section,        having an axially-orthogonal cross-sectional area that is larger        than an axially-orthogonal cross-sectional area of said metallic        chip.

In accordance with this constitution, plasma in liquid generates at theleading end of the metallic chip, not at the leading end of theelectrode conductor that has a non-edge configuration, and thereby themetallic chip is damaged so that nanometer-size particles are beingsynthesized. Since the plasma is caused to generate at the leading endof the metallic chip, damages to the electrode conductor are suppressed.Moreover, since the metallic chip is fed out by means of the feed deviceto a position at which it faces to the leading end of the electrodeconductor, it is possible to synthesize nanometer-size particles quicklyand continuously. Moreover, since the metallic chip makes a rawmaterial, it is not necessary to employ any acid, so that any liquids(such as alcohols), which do not turn into any waste fluids, will do.The “non-edge configuration” is a configuration that is free from anyedge, and in which plasma is less likely to generate on that site; andcan be, for example, convexed arc shapes, planar shapes, orconfigurations in which convexed arc shapes and planar shapes arecombined, and the like.

In the present invention, it is preferable that thenanometer-size-particle production apparatus can comprise the electrodeconductor having the leading-end section whose configuration is aconvexed arc shape. This makes it possible to suppress the generation ofplasma at the leading end of the electrode conductor, and thereby it ispossible to facilitate the generation of plasma at the leading end ofthe metallic chip, so that it is possible to suppress damages to theelectrode conductor more securely.

Moreover, in the present invention, it is preferable that thenanometer-size-particle production apparatus can comprise an electrodehaving: an inner conductor; a dielectric being disposed on an outercircumference of said inner conductor; and an outer conductor beingdisposed on an outer circumference of said dielectric; that a leadingend of said inner conductor, a leading end of said dielectric, and aleading end of said outer conductor can be disposed on an identicalplane; and that said electrode conductor can be said inner conductor.Making the electrode conductor of the aforementioned electrode's innerconductor leads to making it possible to supply a high-frequency wave ormicrowave into the liquid more securely. Moreover, putting the leadingends of the respective constituent elements of the electrode atpositions equally on an identical plane all together results indisposing the rim of the inner conductor's leading end (e.g., aconvexed-arc-shaped section) on a more inner side than is thedielectric's leading end, so that it is possible to prevent plasma fromgenerating at a contact part between the inner conductor and thedielectric. This makes it feasible to prevent damages to the electrode(to the dielectric, especially).

In the present invention, it is preferable that thenanometer-size-particle production apparatus can comprise said innerconductor having a melting point that is greater than a melting point ofsaid metallic chip. This makes it possible to cause plasma to generateat the leading end of the metallic chip more securely.

Moreover, in the pre sent invention, it is preferable that thenanometer-size-particle production apparatus can further comprise aliquid circulation device for not only supplying said liquid into saidcontainer but also discharging said liquid from within said container.This makes it possible to circulate the liquid continuously, so that itbecomes feasible to synthesize nanometer-size particles morecontinuously.

Moreover, it is possible to set forth the present invention as ananometer-size-particle production process. That is, the presentinvention is a nanometer-size-particle production process forsynthesizing nanometer-size particles into a liquid by means of plasmain liquid; and includes:

-   -   a disposition step of face-to-face disposing, within said        liquid, a metallic chip above the leading-end upside of an        electrode conductor in which a covering portion is disposed;    -   a supply step of supplying a high-frequency wave, or a        microwave, into said liquid by way of said electrode conductor;        and    -   a feed step of feeding out said metallic chip toward said        electrode conductor;    -   a leading-end section of said electrode conductor having a        configuration that is a non-edge configuration; and    -   said electrode conductor, except for the leading-end section,        having an axially-orthogonal cross-sectional area that is larger        than an axially-orthogonal cross-sectional area of said metallic        chip.

-   This causes the same advantageous effects as those aforementioned to    demonstrate.

Note herein that said liquid being pure water, and said metallic chipbeing formed of magnesium make it possible to produce nanometer-sizeparticles comprising: zinc nanometer-size particles; and zinc oxidenanometer-size particles being disposed so as to surround a periphery ofsaid zinc nanometer-size particles.

Moreover, said liquid being pure water, and said metallic chip beingformed of magnesium makes it possible to produce magnesium hydroxidenanometer-size particles having a plate shape, and being formed as ahexagon, or a triangle.

In accordance with the present invention, quick and continuous synthesesbecome feasible while suppressing damages to electrodes, without everletting any waste fluids out. The present process makes it possible toproduce nanometer-size particles having a specific structure orconfiguration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram for illustrating the constitution of ananometer-size-particle production apparatus 1 according to a FirstEmbodiment Mode;

FIG. 2 is a flow diagram for illustrating steps according to the FirstEmbodiment Mode;

FIG. 3 is a diagram for illustrating powers and feed rates in EmbodimentNo. 1;

FIG. 4 is a diagram (namely, a photograph) for illustrating the resultsof an observation on the post-synthesis liquid in Embodiment No. 1 by anelectron microscope;

FIG. 5 is a graph for illustrating the results of an analysis by meansof XRD in Embodiment No. 1;

FIG. 6 is a diagram for illustrating powers and feed rates in EmbodimentNo. 2;

FIG. 7 is a diagram (namely, a photograph) for illustrating the resultsof a 50-nm-level observation on the post-synthesis liquid in EmbodimentNo. 2 by an electron microscope;

FIG. 8 is a diagram (namely, a photograph) for illustrating the resultsof a 200-nm-level observation on the post-synthesis liquid in EmbodimentNo. 2 by an electron microscope;

FIG. 9 is a graph for illustrating the results of an analysis by meansof XRD in Embodiment No. 2;

FIG. 10 a diagram for illustrating powers and feed rates in EmbodimentNo. 3;

FIG. 11 is a diagram (namely, a photograph) for illustrating the resultsof an observation on the post-synthesis liquid in Embodiment No. 3 by anelectron microscope;

FIG. 12 is a graph for illustrating the results of an analysis by meansof XRD in Embodiment No. 3;

FIG. 13 a diagram for illustrating powers and feed rates in EmbodimentNo. 4;

FIG. 14 is a diagram (namely, a photograph) for illustrating the resultsof an observation on the post-synthesis liquid in Embodiment No. 4 by anelectron microscope;

FIG. 15 is a graph for illustrating the results of an analysis by meansof XRD in Embodiment No. 4;

FIG. 16 is a diagram for illustrating powers and feed rates inEmbodiment No. 5;

FIG. 17 is a diagram (namely, a photograph) for illustrating the resultsof an observation on the post-synthesis liquid according to EmbodimentNo. 5 by an electron microscope in a case where a container innerpressure was 20 kPa;

FIG. 18 is a diagram (namely, a photograph) for illustrating the resultsof an observation on the post-synthesis liquid according to EmbodimentNo. 5 by an electron microscope in a case where a container innerpressure was 101 kPa;

FIG. 19 is a graph for illustrating distributions of particle diametersof synthesized particles in Embodiment No. 5;

FIG. 20 is a graph for illustrating the results of an analysis by meansof XRD in Embodiment No. 5;

FIG. 21 is a graph for illustrating the results of an analysis by meansof an absorption spectrophotometer in Embodiment No. 5; and

FIG. 22 is a schematic diagram for illustrating the constitution of ananometer-size-particle production apparatus 10 according to a SecondEmbodiment Mode.

MODE FOR CARRYING OUT THE INVENTION

Next, while giving preferred embodiment modes, the present inventionwill be explained in more detail.

First Embodiment Mode

As illustrated in FIG. 1, a nanometer-size production apparatus 1according to a First Embodiment Mode is mainly equipped with a container2, a microwave generation device 3, an electrode 4, a plate 5, ametallic wire 6, a feed device 7, and a waveguide 8.

The container 2 is one which is capable of accommodating a liquidtherein, and accommodates a liquid, such as alcohol or pure water, inthe interior. In the First Embodiment Mode, the container 2 is sealed,because the top is plugged with a lid 21 and the bottom is plugged witha leading-end section of the electrode 4.

The microwave generation device 3 is a device for generating microwaves.In the First Embodiment Mode, a microwave whose frequency is about 2.45GHz is generated by means of a magnetron. The microwave is sent to theelectrode 4 by way of the waveguide 8, and is then supplied into theliquid from the leading end of the electrode 4.

The electrode 4 comprises an inner conductor 41, a dielectric 42 beingdisposed on an outer circumference of the inner electrode 41, and anouter conductor 43 being disposed on an outer circumference of thedielectric 42; and is an electrode in which each of the constituentelements is formed in a coaxial manner. The leading-end section of theelectrode 4 plugs the lower opening of the container 2, therebyconstituting the bottom of the container 2. In other words, theleading-end section of the electrode 4 makes contact with the liquidinside the container 2.

The inner conductor 41 (being equivalent to the “electrode conductor”)is a cylindrical conductor, and is formed of copper in the FirstEmbodiment Mode. A leading-end section 41 a of the inner conductor 41 isformed as a non-edge configuration (or an edge-free configuration) thatdoes not have any corners. To be concrete, the leading-end section 41 aof the inner conductor 41 has a configuration (or a leading-endconfiguration) being formed as a convexed arc shape that protrudes witha gentle curved surface. The leading-end section 41 a makes contact withthe liquid inside the container 2. The inner conductor 4, except for theleading-end section 41 a (or a convexed-arc-shaped part), has a diameterof about 10 mm. A trailing-end section 41 b of the inner conductor 41 isinserted into the waveguide 8.

The dielectric 42 is cylindrical, and is disposed on an outercircumference of the inner conductor 41 in a coaxial manner. Thedielectric 42 is formed of polytetrafluoroethylene. Aninner-circumferential face of the dielectric 42 makes contact with anouter-circumferential face of the inner conductor 41. Note herein thatthe rim of the leading-end section 41 a of the inner conductor 41 ispositioned nearer toward the trailing-end side of the dielectric 42 thanis the leading end of the dielectric 42. In other words, the rim in theleading end of the inner conductor 41 is positioned on a more inner sidethan is the leading end of the dielectric 42. The “rim in theleading-end section 41 a” is an outer-circumferential fraction of a partin the leading-end section 41 a that makes the maximum diameter in theaxially-orthogonal cross section of the leading-end section 41 a.

The outer conductor 43 is a cylindrical conductor, and is disposed on anouter circumference of the dielectric 42 in a coaxial manner. The outerconductor 43 is formed of copper. An inner-circumferential face of theouter conductor 43 makes contact with an outer-circumferential face ofthe dielectric 42. Note that a material of the outer conductor 43 can beany material in which electricity is likely to flow, because it does notaffect the field for synthesizing nanometer-size particles. Theelectrode 4 according to the present embodiment mode is formed so thatthe leading end of the inner conductor 41 (or its leading-end positionof the leading-end section 41 a), the leading end of the dielectric 42(or its leading-end face), and the leading end of the outer conductor 43(or its leading-end face) are positioned on an identical plane. In otherwords, the leading-end position of each of the constituent elements inthe electrode 4 is arranged uniformly or held equally at an identicalheight substantially. Note that the phrase, “being positioned on anidentical plane,” involves “being positioned on an identical planesubstantially,” because some errors are permissible therein.

The plate 5 (being equivalent to the “covering portion”) is aflat-plate-shaped member, and is disposed into the liquid inside thecontainer 2 so as to cover the central upside in the leading end of theelectrode 4 (i.e., a part of the inner conductor 41, dielectric 42 andouter conductor 43). To put it differently, the plate 5 is disposed toface to the leading end of the electrode 4. The plate 5 is disposed toseparate away from the leading end of the electrode 4 by from 3 to 5 mm.The plate 5 is fixed to the outer conductor 43 partially by means offastening members, such as screws. At a part of the plate 5 that facesto the inner conductor 41, a through hole 51 for letting alater-described metallic wire 6 go through is formed. A lower face ofthe plate 5 can have a configuration that is capable of temporarilyretaining bubbles therein.

The metallic wire 6 (being equivalent to the “metallic chip”) is formedof a metal, namely, a raw material of nanometer-size particles. Aleading end of the metallic wire 6 is disposed to face to the leadingend of the inner conductor 41. A separation distance (“x”) between theleading end of the metallic wire 6 and the leading end of the innerconductor 41 can be 2 mm or less (i.e., 0<“x”≦2 mm), and is from about 1to 2 mm in the First Embodiment Mode. That is, the leading end of themetallic wire 6 is disposed to be separated away from and be inproximity with respect to the leading end of the inner conductor 41.However, even in a case where the leading end of the metallic wire 6makes contact with the leading end of the inner conductor 41 (i.e.,“x”=0), plasma generates at around a leading-end section of the metallicwire 6 itself, so that the advantageous effects of the present inventioncan be demonstrated when a melting point of the inner conductor 4 ishigher than a melting point of the metallic wire 6. A diameter of themetallic wire 6 is about 2 mm approximately. That is, anaxially-orthogonal cross-sectional area of the metallic wire 6 issmaller than an axially-orthogonal cross-sectional area of the innerconductor 41 (except for the leading-end section 41 a). The metallicwire 6 is wound around a drum, and the like, on the trailing-end side(i.e., on the upper side in FIG. 1). The term, “axially-orthogonal crosssection,” means a cross section of the constituent elements upon cuttingthem in a direction that crosses the axial direction (or thelongitudinal direction) perpendicularly.

The feed device 7 is one which has been known publicly, and is a devicefor feeding out the metallic wire 6 with respect to the inner conductor41. The feed device 7 pinches the metallic wire 6 between the two rolls,and then rotates the rolls to feed the metallic wire 6 downward. In theFirst Embodiment Mode, a feed rate of the feed device 7 is set updepending on a power for causing plasma to generate.

The waveguide 8 is one for conducting the microwave, which has generatedat the microwave generation device 3, to the electrode 4. With one ofthe opposite end sides of the waveguide 3, the electrode 4 is connected;whereas, with the other one of the opposite end sides, the microwavegeneration device 3 is connected. Since the waveguide 8 is one which hasbeen known publicly, the detailed explanations will be abbreviatedherein.

In addition to those above, the nanometer-size-particle productionapparatus 1 is further equipped with a pressure gauge “A,” a vacuum pump“B,” a pressure adjustment valve “C,” a stub tuner “D,” and a plunger“E,” and so on. Using the pressure gauge “A,” vacuum pump “B” andpressure adjustment valve “C” makes it possible to adjust a pressureinside the container 2. By means of the stub tuner “D” and plunger “E,”matching operations are carried out; moreover, by means of a not-showncoaxial waveguide converter, it is possible to make adjustments so as tomake it possible to supply energy from the microwave generation device 3to the reaction field efficiently. The microwave is transmitted througha coaxial cable line in a TEM mode.

Explanations will be made hereinafter on operations and advantageouseffects of the First Embodiment Mode. First of all, the microwavegeneration device 3 causes the microwave to generate. The microwaveconducts through the waveguide 8, and is eventually transmitted to theelectrode 4 (i.e., the inner conductor 41). The microwave is given fromthe leading-end section 41 a of the inner conductor 41 to the liquidinside the container 2. Then, plasma in liquid generates, not at aroundthe leading end of the inner conductor 41, but at around the leading endof the metallic wire 6 whose diameter is smaller than that of the innerconductor 41. Since the leading end of the inner conductor 41 has aconfiguration being formed as a convexed arc shape that is free fromedges entirely, plasma becomes less likely to generate at the leadingend of inner conductor 41. Thus, plasma generates at the leading end ofthe metallic wire 6, namely, a raw material, and thereby the leading endof the inner conductor 41 can be protected from being damaged by meansof the resulting plasma. Since the resultant plasma is a hightemperature, bubbles generate simultaneously with the generation of theplasma.

The bubbles, which have been generated by means of the plasma into theliquid, are kept from rising by means of the plate 5, and are therebyretained between the plate 5 and the electrode 4, so that the bubblesalways fill up between them during syntheses. The metallic wire 6 (i.e.,a material of nanometer-size particles), which has been vaporized bymeans of the plasma during this time, condenses, and therebynanometer-size particles are synthesized. A gas-temperature rise isbrought about by means of retaining the bubbles between the plate 5 andthe electrode 4, thereby making high-rate syntheses of nanometer-sizeparticles feasible. Although the leading end of the metallic wire 6 isbeing damaged by the vaporization resulting from the plasma, it is fedout to the predetermined face-to-face position successively by means thefeed device 7. In other words, a nanometer-size-particle workpiece issupplied continuously to a position at which it faces to the leading endof the inner conductor 41. Thus, in accordance with the First EmbodimentMode, it is possible to quickly and continuously synthesizenanometer-size particles into liquids.

As illustrated in FIG. 2, a nanometer-size-particle production processaccording to the First Embodiment Mode comprises: a disposition step(i.e., Step “S1”) of face-to-face disposing, within the liquid, theleading end of the metallic wire 6 with respect to an electrodeconductor in which the plate 5 is disposed above the leading-end upside;a supply step (i.e., Step “S2”) of supplying the microwave (or energyresulting from the microwave) into the liquid by way of the innerconductor 41; and a feed step (i.e., Step “S3”) of feeding out theleading end of the metallic wire 6 toward the inner conductor 41. And,the inner conductor 41, except for the leading-end section 41 a, has anaxially-orthogonal cross-sectional area that is larger than anaxial-orthogonal cross-sectional area of the metallic wire 6; and theleading end of the inner conductor 41 has a configuration that makes aconvexed arc shape. In the feed step (i.e., Step “S3”), the metallicwire 6 can be fed out by means of electric power or manual operations incompliance with damages to the leading end of the metallic wire 6.

Embodiment No. 1

Explanations will be made on Embodiment No. 1 in which nanometer-sizeparticles were synthesized using the present apparatus (or the presentprocess). As the metallic wire 6, zinc with 2 mm in diameter was used.As for the liquid, ethanol was used in an amount of 100 mL. A pressureinside the container 2 (or a container inner pressure) was set at 20kPa. Plasma was caused to generate into the liquid by a microwave whosefrequency was 2.45 GHz. A feed rate of the feed device 7 was set up incompliance with powers upon causing the plasma to generate. To beconcrete, the feed rate was set at 7 mm/minute with respect to a powerof 158 W; the feed rate was set at 8 mm/minute with respect to a powerof 171 W; and the feed rate was set at 9 mm/minute with respect to apower of 186 W, as shown in FIG. 3.

By means of those above, nanometer-size particles having about 10 nmapproximately were synthesized. The results (or a photograph) ofobserving the post-synthesis liquid (i.e., the synthesized particles) byan electron microscope are shown in FIG. 4. This photograph is the onein which the nanometer-size particles were synthesized by 186 W.According to the results of an analysis by means of XRD, it becameapparent that zinc nanometer-size particles were synthesized, as shownin FIG. 5. The vertical axis in FIG. 5 (i.e., the results of an analysisby means of XRD) specifies the diffraction intensities; whereas thehorizontal axis in FIG. 5 specifies the incident angles. The synthesisrate was from about 10 to 12 grams per hour.

Embodiment No. 2

Explanations will be made on Embodiment No. 2 in which nanometer-sizeparticles were synthesized using the present apparatus (or the presentprocess). As the metallic wire 6, zinc with 2 mm in diameter was used.As for the liquid, pure water was used in an amount of 100 mL. Acontainer inner pressure was set at 20 kPa. Plasma was caused togenerate into the liquid by a microwave whose frequency was 2.45 GHz. Afeed rate of the feed device 7 was set up in compliance with powers uponcausing the plasma to generate. To be concrete, the feed rate was set at4.3 mm/minute with respect to a power of 133 W; the feed rate was set at6.6 mm/minute with respect to a power of 161 W; and the feed rate wasset at 9.3 mm/minute with respect to a power of 200 W, as shown in FIG.6.

By means of those above, one including sharp-tipped nanometer-sizeparticles having about 100 nm approximately was synthesized. The results(or photographs) of observing the post-synthesis liquid (i.e., thesynthesized particles) by an electron microscope are shown in FIG. 7 andFIG. 8. These photographs are the one in which the nanometer-sizeparticles were synthesized by a power of 133 W, respectively. Accordingto the results of an analysis by means of XRD, it became apparent thatzinc and zinc oxide nanometer-size particles were synthesized, as shownin FIG. 9. The zinc oxide nanometer-size particles were those whose tipswere pointed, as shown in FIG. 7; whereas the zinc nanometer-sizeparticles were formed as a hexagon or circle, as shown in FIG. 8. Inother words, nanometer-size particles, which had been produced by thisprocess, included nanometer-size particles having such a structure thatthe zinc oxide nanometer-size particles surrounded around the peripheryof the zinc nanometer-size particles as shown in FIG. 8. Taking the factthat some of them had oxidized, the synthesis rate was about 14 gramsper hour.

Embodiment No. 3

Explanations will be made on Embodiment No. 3 in which nanometer-sizeparticles were synthesized using the present apparatus (or the presentprocess). As the metallic wire 6, magnesium with 1.6 mm in diameter wasused. As for the liquid, pure water was used in an amount of 100 mL. Acontainer inner pressure was set at 20 kPa. Plasma was caused togenerate into the liquid by a microwave whose frequency was 2.45 GHz. Afeed rate of the feed device 7 was set up in compliance with powers uponcausing the plasma to generate. To be concrete, the feed rate was set at72 mm/minute with respect to a power of 162 W; and the feed rate was setat 88 mm/minute with respect to a power of 177 W, as shown in FIG. 10.

By means of those above, hexagonal (including truncated-triangular ones)or triangular nanometer-size particles having about 100 nm approximatelywere synthesized. The results (or a photograph) of observing thepost-synthesis liquid (i.e., the synthesized particles) by an electronmicroscope are shown in FIG. 11. This photograph is the one in which thenanometer-size particles were synthesized by a power of 162 W. Accordingto the results of an analysis by means of XRD, it became apparent thatmagnesium hydroxide nanometer-size particles were synthesized, as shownin FIG. 12. The synthesis rate was about 60 grams per hour.

Embodiment No. 4

Explanations will be made on Embodiment No. 4 in which nanometer-sizeparticles were synthesized using the present apparatus (or the presentprocess). As the metallic wire 6, silver with 1 mm in diameter was used.As for the liquid, pure water was used in an amount of 100 mL. Acontainer inner pressure was set at 20 kPa. Plasma was caused togenerate into the liquid by a microwave whose frequency was 2.45 GHz. Afeed rate of the feed device 7 was set up in compliance with powers uponcausing the plasma to generate. To be concrete, the feed rate was set at1.4 mm/minute with respect to a power of 200 W; and the feed rate wasset at 1.7 mm/minute with respect to a power of 222 W, as shown in FIG.13.

By means of those above, nanometer-size particles having about 20 nmapproximately were synthesized. The results (or a photograph) ofobserving the post-synthesis liquid (i.e., the synthesized particles) byan electron microscope are shown in FIG. 14. This photograph is the onein which the nanometer-size particles were synthesized by a power of 222W. According to the results of an analysis by means of XRD, it becameapparent that silver nanometer-size particles were synthesized, as shownin FIG. 15. The synthesis rate was about 0.8 grams per hour.

Embodiment No. 5

Explanations will be made on Embodiment No. 5 in which nanometer-sizeparticles were synthesized using the present apparatus (or the presentprocess). As the metallic wire 6, tungsten with 1 mm in diameter wasused. As for the liquid, pure water was used in an amount of 100 mL.With regard to the container inner pressure, the synthesis was carriedout in each of the following cases: when it was set at 20 kPa; and whenit was set at 101 kPa. Plasma was caused to generate into the liquid bya microwave whose frequency was 2.45 GHz. A feed rate of the feed device7 was set up in compliance with powers upon causing the plasma togenerate. To be concrete, regardless of the container inner pressures,the feed rate was set at 6.2 mm/minute with respect to a power of 150 W;and the feed rate was set at 11.1 mm/minute with respect to a power of200 W, as shown in FIG. 16.

As a consequence of the synthesis, nanometer-size particles having 30 nmor less in diameter were synthesized even at any of the container innerpressures (i.e., 20 kPa, and 101 kPa). The post-synthesis liquid (i.e.,the synthesized particles), which had undergone the synthesis by a powerof 200 W at each of the container inner pressures, was analyzed by meansof an electron microscope, XRD, and an absorption spectrophotometer. Theresults (or photographs) of the observation by an electron microscopeare shown in FIG. 17 and FIG. 18, respectively. Moreover, thedistributions of particle diameters of the synthesized particles are inshown FIG. 19.

As illustrated in FIG. 19, a large number of single-crystallineparticles, which were formed as a sphere with 8 nm approximately indiameter, were observed in the nanometer-size particles that weresynthesized under 20 kPa. Meanwhile, in another case where the synthesiswas done under 101 kPa, sphere-shaped nanometer-size particles with 14nm in diameter were observed most abundantly. In addition to those,quadrangular or diamond-shaped particles with such a large size as 50 nmwere also ascertained, as shown in FIG. 18. When analyzing theconfigurations of the resulting particles, it is believed that thelarge-sized particles appeared a diamond or rectangle depending on theviewing angle, because they were diamond-shaped polygonal columns. Thevertical axis in FIG. 19 specifies the frequencies; whereas thehorizontal axis in FIG. 19 specifies the diameters.

The results of the analysis by means of XRD are shown in FIG. 20. Asillustrated in FIG. 20, the synthesized particles were identified to betungsten trioxide nanometer-size particles even at any of the containerinner pressures. Moreover, the post-synthesis liquid had a color thatchanged depending on the container inner pressures during the synthesis.In a case where the synthesis was done at 20 kPa, the post-experimentsolution was colored in a dark blue; whereas, in another case where thesynthesis was done at 101 kPa, it turned into a solution having awhitish blue color. The results of the analysis by means of anabsorption spectrophotometer are shown in FIG. 21. As illustrated inFIG. 21, it was ascertained that the physical property of nanometer-sizeparticles to be synthesized changes depending on differences in thecontainer inner pressures. The vertical axis in FIG. 21 specifies theabsorbances; whereas the horizontal axis in FIG. 21 specifies thewavelengths. When the synthesis was done by a power of 200 W, thesynthesis rate was, regardless of the container inner pressures, about10 grams per hour.

If the inner conductor 41 should have been damaged so that the innerconductor 41 should have shortened, it should become impossible to dothe continuous synthesis because no plasma should generate. InEmbodiment Nos. 1 through 5, since it was possible to synthesize thenanometer-size particles continuously, and since the metallic wire 6 hadshortened, it is understood that the plasma generated at the leading endof the metallic wire 6. Moreover, the spectrum of the conductor 41 wasnot detected at all even in the results of the analysis by means of XRD,it is also understood that the conductor 41 were kept from beingdamaged. In the First Embodiment Mode, since all of the metallic wire 6turned into particles to the extent that it had been supplied, highsynthesis rates could be achieved.

As described so far, in accordance with the First Embodiment Mode, it ispossible to synthesize nanometer-size particles quickly and continuouslywhile suppressing damages to the inner conductor 41. Moreover, since itis not necessary to use an acid as the liquid, it is possible to usealcohols and water that do not turn into any waste fluids. In otherwords, it is possible to prevent the occurrence of waste fluids.

Modified Embodiments

The present invention is not limited at all to the aforementionedembodiment modes. For example, the feed device 7 is not limited at allto those which feed out the metallic wire 6 automatically. The feeddevice 7 can be those which are capable of retaining the metallic wire 6so as to make the leading-end position adjustable with respect to theinner conductor 41. Feeding (or moving) the metallic wire 6 can also bedone manually.

Moreover, a configuration that the inner conductor 41 has at the leadingend can be a planar shape, too. In this case, it is preferable that theleading ends of the electrode 4 can be flush (or in a flat state) witheach other. The “convexed arc shape” can be curved surfaces, like a partof spherical surfaces, for instance. Moreover, it is also allowable thatthe leading end of the inner conductor 41 can have a planar shape at thecentral section as well as a convexed arc shape at the rim therearound.For example, it is even permissible that the leading end of the innerconductor 41 can be those which have been chamfered so as to make smoothedges around the rim. These configurations are a configuration, whichinhibits plasma from generating at the leading end of the innerconductor 41 but which causes plasma to generate at the leading end ofthe metallic wire 6, respectively. The leading end of the innerconductor 41 cannot necessarily have a configuration that makes apointed configuration, but can have configurations that make plasma lesslikely to generate.

Moreover, it is preferable that the inner conductor 41, except for theleading-end section 41 a, can have a diameter of 6 mm or more;practically, however, being from 6 to 15 mm is preferable. In contrastto this, it is preferable that the metallic chip can have from 1 to 3mm. It is preferable that a ratio of the diameter of the metallic wire 6to the diameter of the inner conductor 41 can make ½ or less;furthermore, being ⅕ or less is preferable.

Moreover, it is also allowable that the electrode 4 can be disposed on aside face of the container 2. In other words, the side face of thecontainer 2 makes contact with the liquid laterally at the leading endof the electrode 4 thereon. In this case, the plate 5 is disposed onthat side face of the container 2, and covers the leading-end upside ofthe inner conductor 41. It is also allowable that metallic wire 6 can besupplied toward the downside through the through hole of the plate 5 inthe same manner as the aforementioned embodiment mode. Alternatively, itis even permissible that the metallic wire 6 can be supplied laterallyfrom another side face that faces to the side face on which theelectrode 4 is disposed.

Moreover, a frequency of the microwave can be selected suitably inaccord with a liquid to be employed and an intended use or purpose forthe resulting plasma; and can be from 100 MHz to 200 GHz approximately.However, utilizing a magnetron whose frequency is 2.45 GHz enablescommon microwave ovens to be used as a microwave generation device, sothat it is possible to keep down the manufacturing costs. Moreover,although it is preferable that the leading-end rim of the innerconductor 41 can be positioned on a more trailing-end side of thedielectric 42 than is the leading end of dielectric 42, it is alsoallowable that the leading-end positions of the respective constituentelements of the electrode 4 cannot necessarily be made equal to eachother. However, when the leading-end section 41 a is formed in aconvexed arc shape as done in the present embodiment mode, positioningthe leading ends of the respective constituent elements of the electrode4 on an identical plane leads to making it possible to dispose the rimof the leading-end section 41 a securely on a more inner side (ortrailing-end side) than is the leading end of the dielectric 42.Disposing the rim of the leading-end section 41 a of the inner conductor41 on a more inner side than is the leading end of the dielectric 42results in making it possible to prevent plasma from generating at thecontact part between the inner conductor 41 and the dielectric 42. Thismakes it feasible to prevent the electrode 4 (or the dielectric 42,especially) from being damaged. Moreover, disposing the leading-endpositions of the respective constituent elements of the electrode 4 onan identical plane leads to striking a balance between the following;protecting the leading end of the inner conductor 41; and making plasmalikely to generate.

Moreover, it is also advisable that the feed device 7 can beelectrically connected to the stub tuner “D,” and to the plunger “E”(see the solid lines in FIG. 1). And, in this case, it is preferablethat the stub tuner “D,” and the plunger “E” can be subjected tomatching automatically, regarding the supply of energy resulting fromthe microwave, so that they become optimum for a feed rate of themetallic wire 6. Interlocking the feed device 7, the stub tuner “D,” andthe plunger “E” with each other (or causing them to do feedback oneanother) results in making the following feasible: setting up anappropriate feed rate, and an appropriate power; and automatizing theirappropriate adjustments.

Moreover, it is allowable to even use a high-frequency-wave generationdevice (not shown), instead of the microwave generation device 3. In thepresent invention, a “high-frequency wave” means electromagnetic waveswhose frequency is from 1 MHz to 100 MHz. These can also generate plasmain liquid, so that the same advantageous effects as those aforementionedcan be demonstrated.

Moreover, the electrode 4 is not limited at all to coaxially-shapedones, but it is allowable that the electrode 4 can even be an antennaelectrode (not shown) comprising rod-shaped conductors. In particular,in the case of a high-frequency wave, it is possible to cause plasma inliquid to readily generate, without ever using any coaxially-shapedelectrode having the outer electrode 43, and so on.

Second Embodiment Mode

As illustrated in FIG. 22, a nanometer-size-particle productionapparatus 10 according to a Second Embodiment Mode further comprises, inaddition to the constituent elements in the nanometer-size-particleproduction apparatus 1 according to the First Embodiment Mode, a pump 9(being equivalent to the “liquid circulation device”) for not onlysupplying the liquid into the container 2 but also discharging theliquid from the container 2. This makes it possible to circulate theliquid continuously within the container 2, and thereby it becomesfeasible to continuously synthesize nanometer-size particles furthermoreeffectively. It is possible to apply the modified embodiments to theSecond Embodiment Mode as well in the same manner as the FirstEmbodiment Mode.

EXPLANATION ON REFERENCE NUMERALS

1, and 10: Nanometer-size-particle Production Apparatuses;

2: Container; 3: Microwave Generation Device (i.e., Electromagnetic-waveGeneration Device);

4: Electrode; 41: Inner Conductor (i.e., Electrode Conductor); 41 a:Leading-end Section;

42: Dielectric; 43: Outer Conductor;

5: Plate (i.e., Covering Portion); 51: Through Hole;

6: Metallic Wire (i.e., Metallic Chip); 7: Feed Device;

8: Waveguide; 9: Pump (i.e., Liquid Circulation Device);

“A”: Pressure Gauge; “B”: Vacuum Pump; “C”: Pressure Adjustment Valve;

“D”: Stub Tuner; and “E”: Plunger

The invention claimed is:
 1. A nanometer-size-particle productionapparatus for synthesizing nanometer-size particles in a liquid by meansof plasma in liquid, the nanometer-size-particle production apparatuscomprising: a container for accommodating said liquid therein; anelectromagnetic-wave generation device for generating a high-frequencywave, or a microwave; an electrode conductor whose leading end makescontact with said liquid to supply said high-frequency wave or saidmicrowave to said liquid; a covering portion being disposed into saidliquid so as to cover a leading-end upside of said electrode conductor;a metallic chip being composed of a metal making a raw material ofnanometer-size particles, and having a leading end that is disposed toface to the leading end of said electrode conductor; and a feed devicefor feeding out the leading end of said metallic chip with respect tothe leading end of said electrode conductor; a leading-end section ofsaid electrode conductor having a non-edge configuration that does nothave any corners; and said electrode conductor, except for theleading-end section, having an axially-orthogonal cross-sectional areathat is larger than an axially-orthogonal cross-sectional area of saidmetallic chip.
 2. The nanometer-size-particle production apparatusaccording to claim 1, wherein the electrode conductor having theleading-end section whose configuration is a convexed arc shape.
 3. Thenanometer-size-particle production apparatus according to claim 2,comprising an electrode having: an inner conductor; a dielectric beingdisposed on an outer circumference of said inner conductor; and an outerconductor being disposed on an outer circumference of said dielectric; aleading end of said inner conductor, a leading end of said dielectric,and a leading end of said outer conductor being disposed on an identicalplane; and said electrode conductor being said inner conductor.
 4. Thenanometer-size-particle production apparatus according to claim 1,wherein said electrode conductor having a melting point that is greaterthan a melting point of said metallic chip.
 5. Thenanometer-size-particle production apparatus according to claim 1,further comprising a liquid circulation means for not only supplyingsaid liquid into said container but also discharging said liquid fromwithin said container.